JP2018066678A - Device for detecting non-conduction in semiconductor switching element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-conduction detection device with which it is possible to detect the occurrence of electrical non-conduction in a semiconductor switching element and specify a semiconductor switching element whose electrical conduction is lost.SOLUTION: Provided is a non-conduction detection device for detecting electrical non-conduction in semiconductor switching elements constituting AC switches 3u, 3v, 3w, 4u, 4v, 4w, each connected between each phase of three-phase AC power supplies 1, 2 and a load 5. This non-conduction detection device comprises: voltage detectors 11-13, full-wave rectifier circuits 21-23, and subtractors 41, 42 for detecting a differential voltage between the input line voltage and the output line voltage of an AC switch; and comparators 31, 32, AND circuits 51, 52, and timekeeping elements 61, 62 for detecting which switching element that constitutes the AC switch is in an electrical non-conduction state when the differential voltage exceeds a prescribed threshold while a gate signal is applied to the AC switch.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for detecting a non-conduction state of a semiconductor switching element that constitutes an AC switch for a power conversion circuit, for example.

As a conventional technique for detecting a non-conduction state of a thyristor constituting an AC switch, for example, a non-conduction detection device described in Patent Document 1 is known.
FIG. 5 is a configuration diagram showing the above-described non-conducting detection device. In FIG. 5, 101 is a three-phase AC power source, 102 is a load, 103u, 103v, and 103w are current detectors for each phase (U, V, and W phases), THua, THub, THva, THvb, THwa, THwa, and THwb are each phase. , A voltage detector that detects a line voltage V _UV between the U and V phases, 110 a synchronization detection circuit that generates a synchronization signal from the line voltage V _UV , and 120 a thyristor of the U phase. This is a non-conduction detection circuit that detects non-conduction of THua or THub.

In the non-conducting detection circuit 120, 121 is a subtractor for delaying the synchronizing signal of the line voltage V _UV by 30 ° to obtain a U-phase voltage synchronizing signal, and 122 is an interrupt at 60 ° intervals from the U-phase voltage synchronizing signal. An interrupt signal generating circuit for generating a signal, 123 is a microcomputer, 123a is a U-phase positive current effective value arithmetic circuit, 123b is a U-phase negative current effective value arithmetic circuit, and 123c is from each of the effective value arithmetic circuits 123a and 123b. A subtractor 124 for obtaining the deviation of the positive and negative current effective values to be output is a comparator 124 that compares the deviation with a detection level and outputs a thyristor non-conduction detection signal.
Each RMS value calculation circuit 123a, 123b is input with a periodic periodic interrupt signal of 400 μs for sampling the U-phase current detection value and performing various calculations in addition to the interrupt signal at intervals of 60 °. .

  Here, the voltage detector 105, the synchronization detection circuit 110, and the non-conduction detection circuit 120 are for detecting the non-conduction of the U-phase thyristor THua or THub, and although not shown, the V-phase thyristor THva or A similar circuit is provided for each of the V phase and the W phase for detecting non-conduction of the THvb and W phase thyristors THwa or THwb.

Next, in this conventional technique, a non-conduction detection operation when either U-phase thyristor THua or THub becomes non-conductive due to a failure will be described with reference to FIG.
Each of the effective value calculation circuits 123a and 123b performs sampling of the U-phase current detection value and calculation of the square value thereof by a periodic periodic interrupt signal of 400 μs, and performs U-phase positive current and U-phase negative current every half cycle of the U-phase voltage. Calculates, holds, and resets the square integral value of. Further, the effective values (rms) of the U-phase positive current and the U-phase negative current are calculated based on these square integral values, and the effective values are updated every half cycle of the U-phase voltage.

Now, either the thyristor THua or THub becomes non-conductive, and U-phase current detection value at time t ₀ in FIG. 6 is lost. In this case, the square integral value of the U-phase negative current is smaller than before, and the effective value of the U-phase negative current is greatly reduced in the data update cycle in the negative period, whereas the effective value of the U-phase positive current is Therefore, the deviation of the effective value of the U-phase current calculated by the subtractor 123c in FIG. 5 becomes a waveform in the second stage from the bottom in FIG.
Therefore, by setting an appropriate non-conduction detection level in the comparator 124, a non-conduction detection signal indicating that either the thyristor THua or THub is non-conductive can be output from the comparator 124. .

JP 2013-24682 (paragraphs [0014] to [0018], [0024], FIG. 1, FIG. 2, etc.)

  In the above-described prior art, in order to detect the non-conduction of all thyristors, it is necessary to provide a synchronization detection circuit, a non-conduction detection circuit, etc. for each phase individually. There was a problem that the thyristor that became conductive could not be identified.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a non-conducting detection device capable of simplifying a circuit configuration and reducing costs and identifying a semiconductor switching element that has become non-conducting.

In order to solve the above problem, the invention according to claim 1
In a non-conducting detection device for detecting a non-conducting state of a semiconductor switching element constituting an AC switch connected between each phase of a three-phase AC power source and a load,
Means for detecting a differential voltage between an input voltage and an output voltage of the AC switch;
One of the semiconductor switching elements constituting the AC switch is in a non-conductive state when the differential voltage exceeds a predetermined threshold in a state where a drive control signal for turning on / off the AC switch is given. Means for generating a non-conduction detection signal indicating
It is provided with.

  According to a second aspect of the present invention, in the semiconductor switching non-conduction detecting device according to the first aspect, the means for detecting the differential voltage is a full-wave rectified waveform of a line voltage input to the AC switch of each phase. And the full-wave rectified waveform of the line voltage output from the AC switch of each phase is detected.

  According to a third aspect of the present invention, in the semiconductor switching element non-conduction detecting device according to the first or second aspect, the semiconductor switching element non-conduction detecting device includes means for detecting a phase of an arbitrary two-phase line voltage of the three-phase AC power source, A means for specifying a semiconductor switching element in a non-conduction state based on a phase and the non-conduction detection signal is provided.

  According to a fourth aspect of the present invention, in the semiconductor switching element non-conducting detection device according to any one of the first to third aspects, the AC switch includes two thyristors connected in antiparallel to each other. It is characterized by.

  According to a fifth aspect of the present invention, in the semiconductor switching element non-conducting detection device according to any one of the first to fourth aspects, the apparatus includes a plurality of power feeding systems including the three-phase alternating current power source and the alternating current switch. When the non-conduction detection signal is detected from the power feeding system and the output voltage of the power feeding system is lowered, the drive control is performed so that power feeding to the load by the power feeding system is stopped and switched to power feeding by another power feeding system. A means for controlling the signal is provided.

According to the present invention, a semiconductor switching element such as any thyristor constituting an AC switch connected to a power supply system from a three-phase AC power source to a load is in a non-conductive state by a relatively simple circuit configuration. Furthermore, it is possible to identify the element which switching element has become non-conductive.
Further, when the non-conduction of the switching element is detected, the power supply system can be quickly switched to switch the power supply, and the power supply to the load can be continued while preventing the occurrence of a cross current to the faulty system.

It is a block diagram of the non-conducting detection apparatus which concerns on embodiment of this invention. It is a wave form diagram which shows operation | movement of embodiment of this invention. It is a wave form diagram which shows operation | movement of embodiment of this invention. It is a wave form diagram which shows operation | movement of embodiment of this invention. It is a block diagram of the prior art described in patent document 1. FIG. It is a wave form diagram which shows operation | movement of the prior art shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The present embodiment detects the non-conducting state of the thyristor constituting the AC switch of the power conversion circuit. However, the target semiconductor switching element is not limited to the thyristor, and various power semiconductor elements such as a power transistor. It may be.

FIG. 1 is a configuration diagram of a non-conducting detection device according to this embodiment.
In FIG. 1, first and second three-phase AC power supplies 1 and 2 are connected via three-phase power lines 6u, 6v and 6w, and a load 5 is connected to these power lines 6u, 6v and 6w. . Further, AC switches 3u, 3v, 3w are respectively connected to the power lines 6u, 6v, 6w between each phase of the three-phase AC power source 1 and the load 5, and each phase of the three-phase AC power source 2 and the load 5 are connected to each other. AC switches 4u, 4v, 4w are also connected to the power lines 6u, 6v, 6w, respectively.
The U-phase AC switch 3u is configured by connecting thyristors SCR ₁₁ and SCR ₁₂ in antiparallel, and the AC switch 4u is configured by connecting thyristors SCR ₂₁ and SCR ₂₂ in antiparallel. The same applies to the AC switches 3v, 3w, 4v, 4w of other phases.

Here, the power supply system to the load 5 including the three-phase AC power source 1 and the AC switches 3u, 3v, and 3w is connected to the load 5 including the one-system power supply system, the three-phase AC power source 2 and the AC switches 4u, 4v, and 4w. Assume that the power supply system is a 2-system power supply system, and the load 5 is supplied with power from the 1-system or 2-system power supply system. When the thyristor constituting the AC switch of one system breaks down and becomes non-conductive, power is supplied to the load 5 from the other power supply system having a healthy thyristor (so-called power conversion is performed). ing.
Note that one type of AC switch 3u, 3 v, by all of the thyristor gate signal (drive control signal) _{G 1} constituting the 3w, 2 system AC switch 4u, 4v, all thyristors constituting the 4w gate signal G ₂ are turned on and off respectively.

A first voltage detection circuit 11 for detecting an input phase voltage to the AC switches 3u, 3v, 3w is connected between the three-phase AC power source 1 and the AC switches 3u, 3v, 3w. And the AC switches 4u, 4v, 4w are connected with a second voltage detection circuit 12 for detecting the input phase voltage to the AC switches 4u, 4v, 4w. A third voltage detection circuit 13 for detecting the output phase voltage of each AC switch is connected between the AC switches 3u, 3v, 3w and the AC switches 4u, 4v, 4w.
The two-phase voltage instantaneous values output from the first to third voltage detection circuits 11, 12, 13 and the remaining one-phase voltage instantaneous values obtained by multiplying the sum by "-1" are The signals are input to the third full-wave rectifier circuits 21, 22, and 23, and full-wave rectified waveforms of the input line voltage are output.

The outputs of the full-wave rectifier circuits 21 and 23 are respectively input to the first subtractor 41 with the illustrated sign, and the output is applied to one input terminal of the first comparator 31. Further, the outputs of the full-wave rectifier circuits 22 and 23 are respectively input to the second subtractor 42 by the sign shown, and the output is applied to one input terminal of the second comparator 32.
A predetermined threshold value is input from the setting device 7 to the other input terminal of each of the first and second comparators 31 and 32.

The output of the comparator 31 is applied to one input terminal of the first AND circuit 51, and the output of the comparator 32 is applied to one input terminal of the second AND circuit 52. The other is the input terminal 1 based AC switch 3u of the AND circuit 51, 3 v, the gate signal _{G 1} is applied against 3w, AC switch 4u of 2 system to the other input terminal of the AND circuit 52, 4v, the gate signal _{G 2} is added for 4w.

The first and second timing elements 61 and 62 are connected to the output sides of the AND circuits 51 and 52, respectively. The output level of the AND circuits 51 and 52 exceeds the set time by the timing elements 61 and 62, and is “High”. At this time, the first and second thyristor non-conduction detection signals S ₁ and S ₂ are output, respectively.
Also, first and second phase detection circuits 71, 71 for detecting the phase of the line voltage _VUV between two phases (for example, U and V phases) output from the first and second voltage detection circuits 11, 12 72 is provided, and the outputs of the phase detection circuits 71 and 72 are input to the first and second non-conducting thyristor specifying circuits 81 and 82, respectively. Note that the line voltage whose phase is detected by the phase detection circuits 71 and 72 is not limited to the line voltage between the U and V phases, but may be any line voltage between any two phases.

The thyristor non-conductive detection signals S ₁ and S ₂ are also input to the non-conductive thyristor specifying circuits 81 and 82, respectively. The non-conductive thyristor specifying circuits 81 and 82 are connected to the phase output from the phase detecting circuits 71 and 72. A non-conductive thyristor is specified according to the thyristor non-conductive detection signals S ₁ and S _2, and non-conductive thyristor specific signals T ₁ and T ₂ are output.

Next, the operation of this embodiment will be described. Here, for example, power is supplied to the load 5 from the three-phase AC power source 1 in the 1-system power supply system via the AC switches 3u, 3v, 3w.
2 shows an input voltage (input line voltage) full-wave rectification waveform output from the full-wave rectification circuit 21, an output voltage (output line voltage) full-wave rectification waveform output from the full-wave rectification circuit 23, An example of the difference voltage between these waveforms and the phase of the line voltage V _UV output from the phase detection circuit 71 is shown.

Now, at time t _F in FIG. 2, the AC switch 3u, 3 v, when any of the thyristors constituting the 3w is to become non-conductive, the output voltage full-wave rectification waveform is decreased input voltage full-wave rectified waveform And a difference voltage is generated between these waveforms.
The difference voltage is detected by the subtractor 41, and when the difference voltage exceeds the threshold value set by the setting unit 7, a signal of “High” level is output from the comparator 31. The AND circuit 51 outputs a “High” level signal based on the logical product of the “High” level signal from the comparator 31 and the gate signal G ₁ .

When the “High” level signal output from the AND circuit 51 continues beyond the time set by the timing element 61, one of the thyristors constituting the AC switches 3u, 3v, 3w becomes non-conductive. A thyristor non-conducting detection signal S ₁ indicating that it has become is output.
Note that the set time by the time measuring element 61 is shorter than, for example, a time corresponding to the phase of 60 ° to 180 ° of the input line voltage (1/3 of one cycle of the input line voltage) for the purpose of preventing erroneous detection. Any time can be used.

Here, FIG. 3, the 1-system AC switch 3u, 3 v, ON period and the input voltage of the six thyristors constituting the 3w (between the input line voltage) full-wave rectified waveform, the line voltage V _UV waveform and phase Is shown.
SCR ₁₁ (u) and SCR ₁₂ (u) in the figure correspond to the thyristors SCR ₁₁ and SCR ₁₂ constituting the U-phase AC switch 3u in FIG. 1, and SCR ₁₁ (v) and SCR ₁₂ (v) are A pair of thyristors SCR ₁₁ (w) and SCR ₁₂ (w) constituting the V-phase AC switch 3v correspond to a pair of thyristors constituting the W-phase AC switch 3w, respectively. Also, V _UV (p) to V _WU (n) written below the SCR ₁₁ (u) to SCR ₁₂ (w) are part of the input line voltage waveform that appears when the thyristor is turned on (in FIG. 2). For example, V _UV (p) is a waveform that appears when the thyristor SCR ₁₁ of the U-phase AC switch 3u is turned on, and V _UV (n) is the same as the U-phase. This waveform appears when the thyristor SCR ₁₂ of the AC switch 3u is turned on.

As is apparent from FIGS. 2 and 3, the line voltage V _UV that generates the differential voltage depends on which thyristor out of the six thyristors constituting the AC switches 3 u, 3 v, 3 w becomes nonconductive. The phase is different. Therefore, the non-conductive thyristor specifying circuit 81 specifies the non-conductive thyristor based on the thyristor non-conductive detection signal S ₁ and the phase information of the line voltage V _UV and outputs the non-conductive thyristor specific signal T _1. can do.

As with the above-described 1-system power supply system, the full-wave rectifier circuits 22 and 23, the subtractor 42, and the 6 thyristors constituting the AC switches 4u, 4v, and 4w in the 2-system power supply system are compared. vessel 32, the aND circuit 52, timing element 62, by the operation of the non-conducting thyristor particular circuit 82, one of the thyristors is to output a detected thyristor nonconductive detection signal S ₂ that has become non-conductive, and further, which thyristors can output the non-conducting thyristor specific signal T ₂ to detect whether becomes nonconductive.

Next, FIG. 4, since the non-conductive one system thyristor feeding the system at the time t _F has occurred, is a waveform diagram showing an operation when switching the power supply system to the load 5 on the 2-based side.
When the thyristor becomes non-conductive in system 1, the circuit is opened in one of the three phases, the output voltage to the load 5 decreases to reach 0 [V], and the three-phase including the healthy phase thyristor Based on the fact that the current flowing through all the thyristors becomes 0 [A], it can be determined that the thyristor OFF condition (the current is equal to or less than the holding current) is satisfied.

Accordingly, when it is confirmed that the thyristor non-conduction detection signal S ₁ and the disappearance of the output voltage and current are confirmed, the gate signal G _{1 applied} to the thyristor in the first power feeding system before the time t _F is turned off, and the second power feeding is performed. to turn on the gate signal G ₂ for the thyristors in the system.
Thus, the time t _F after the healthy AC switch 4u by 2 system power supply system of, 4v, can provide power to the load 5 through a 4w, can be completed so-called power conversion operation.

In addition, although the said embodiment demonstrated the power supply conversion circuit which has two electric power feeding systems with respect to the load 5, this invention is applicable also to the power supply conversion circuit which has three or more electric power feeding systems.
Furthermore, the non-conducting detection principle of the switching element and the specific principle of the non-conducting switching element in the present invention are applied to a single power feeding system that feeds a load via an AC switch connected to each phase of a three-phase AC power source. Can also be applied.

  The present invention can be used in a power supply conversion circuit and a redundant power supply circuit for a three-phase load.

1, 2: Three-phase AC power supply 3u, 3v, 3w, 4u, 4v, 4w: AC switch 5: Load 6u, 6v, 6w: Power line 7: Setters 11, 12, 13: Voltage detection circuits 21, 22, 23 : Full wave rectifier circuit 31, 32: comparator 41, 42: subtractor 51, 52: AND circuit 61, 62: timing element 71, 72: phase detection circuit 81, 82: non-conducting thyristor specifying circuit

Claims (5)

In a non-conducting detection device for detecting a non-conducting state of a semiconductor switching element constituting an AC switch connected between each phase of a three-phase AC power source and a load,
Means for detecting a differential voltage between an input voltage and an output voltage of the AC switch;
One of the semiconductor switching elements constituting the AC switch is in a non-conductive state when the differential voltage exceeds a predetermined threshold in a state where a drive control signal for turning on / off the AC switch is given. Means for outputting a non-conduction detection signal indicating
A non-conducting device for detecting a semiconductor switching element. In the semiconductor switching non-conducting detection device according to claim 1,
The means for detecting the differential voltage is a difference voltage between a full-wave rectified waveform of a line voltage input to the AC switch of each phase and a full-wave rectified waveform of a line voltage output from the AC switch of each phase. A non-conducting detection device for a semiconductor switching element, characterized in that: In the non-conducting detection device of the semiconductor switching element according to claim 1 or 2,
Means for detecting the phase of any two-phase line voltage of the three-phase AC power source;
A non-conducting detection device for a semiconductor switching element, comprising means for specifying a non-conducting semiconductor switching element based on the phase and the non-conducting detection signal. In the non-conducting detection device of the semiconductor switching element given in any 1 paragraph of Claims 1-3,
The AC switching device includes two thyristors connected in antiparallel to each other, and the semiconductor switching element non-conducting detection device. In the non-conducting detection apparatus of the semiconductor switching element described in any one of Claims 1-4,
A plurality of power supply systems having the three-phase AC power source and the AC switch,
When the non-conduction detection signal is detected from one power supply system and the output voltage of the power supply system is lowered, the power supply to the load by the power supply system is stopped and switched to power supply by another power supply system. A non-conducting detection device for a semiconductor switching element, comprising means for controlling a drive control signal.

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